The present invention relates to an inverter device that includes an alternating current-direct current conversion unit that converts an alternating current input into a direct current, a smoothing capacitor that smoothes the output of the alternating current-direct current conversion unit, and a direct current-alternating current conversion unit that converts a direct current input into an alternating current, and that is provided with a cooling fin that carries a heat-generating component constituting the alternating current-direct current conversion unit and the direct current-alternating current conversion unit, and more particularly to a cooling capacity measurement method for an inverter device that can measure the decrease in cooling capacity caused by clogging of the cooling fin or decrease in the rotation speed due to finite service life of a cooling fan provided at the cooling fin.
In the inverter device of this type, a heat-generating component such as a rectifying diode or an IGBT that is a constituent component of the alternating current-direct current conversion unit and the direct current-alternating current conversion unit is placed on a cooling fin provided with a large number of fin portions, heat from the heat-generating component is conducted to the cooling fin and the heat is dissipated by a forced cooling system in which air is blown onto the cooling fin by a cooling fan and heat exchange is conducted.
The cooling fan is a component with a finite service life, and in order to extend the service life of the cooling fan, the temperature of the cooling body on which the heat-generating component is installed is detected and the cooling fan is started and stopped depending on the detected temperature value, for example, as disclosed in Japanese Patent Application Laid-open No. H7-154976.
According to Japanese Patent Application Laid-open No. H7-154976, the service life of the cooling fan can be extended, but because a function of predicting the end point of service life of the cooling fan is not provided, the end of service life of the cooling fan is detected for the first time when the cooling fan fails.
In other words, when the cooling fan is used for a long time, the mount of air blown by the fan decreases because of limited service life. As a result the cooling capacity also decreases. When the cooling capacity thus decreases, the temperature rises and a usability standard value of the heat-generating components such as IGBT is exceeded.
In the conventional system, the absolute value of temperature is detected with a temperature detector mounted on the cooling body, and in a case where the absolute value of temperature detected by the temperature detector exceeds the preset reference value, the service life of the cooling fan is determined to have ended, the protection of the inverter device is stopped and a display alarm signal is produced.
However, in such conventional system, because the service life end of the cooling fan is determined by the absolute value of temperature detected by the temperature detector mounted on the cooling body, the protection function is active with respect to the increase in ambient temperature, state of the load, and overloading, even if the cooling capacity of the cooling fan does not drop.